Implantable tissue augmentation devices and tissue replacement devices have been used for many years for the augmentation or replacement of damaged biological tissue where this tissue provided the mechanical connection and support responsible for the forces involved in moving related anatomical structures, this tissue generally being in the form of ligaments and tendons. Tissue augmentation devices are used to augment the function of biological tissue, i.e. such devices will carry a portion of any imposed mechanical loads and will assist the biological tissue in carrying such loads, either temporarily, during healing of damaged biological tissue, or permanently. Tissue replacement devices carry the entire mechanical load and so replace the function of the biological tissue. Both tissue augmentation devices and tissue replacement devices are hereinafter collectively referred to as tissue repair devices.
There are many specific applications of tissue repair devices. For example, they are utilized for shoulder rotator cuff repair, acromioclavicular separations, and ligaments of the knee such as anterior cruciate and medial and lateral collateral. Additional examples include the repair of lateral collateral ligaments of the ankle and the repair of large tendons such as the achilles, quadriceps and patellar tendons, and small tendons such as flexor and extensor tendons of the hand.
Tissue repair devices for either replacement or augmentation are most typically manufactured of biocompatible polymers such as polytetrafluoroethylene (hereinafter PTFE), porous PTFE, polyester, polyamide, polypropylene or polyethylene terephthalate. They may also be made entirely or partly of biodegradable materials. The construction of tissue repair devices comprised at least partly of biodegradable materials is taught by U.S. Pat. Nos. 4,759,765; 4,772,288; and 4,792,336, and by European Patent Application No. 0241252A2. Such devices are typically of rope or cord-like form made of multiple strands that may be braided or woven together. They may incorporate an eyelet at one or both ends, the eyelet being intended to accept a bone screw for attaching the eyelet end of the device to an adjacent bone.
Single eyelet devices have also been used for cerclage applications in which the length of the single eyelet device encircles the member or members to which it is to be attached, the end of the device opposite the eyelet being inserted through the eyelet and pulled taut. The second end of the device is then attached back to the encircling part of the device or to a separate attachment point. Cerclage techniques have been used for the repair of, for example, incompetent uterus and for ileocecal bypass. The advantage of this type of repair is that the tissue repair device is only required to be attached by the surgeon at the end opposite the eyelet, thus saving operational time and expense.
The eyelets of previous tissue repair devices have often been formed by bending the length of material back on itself at its longitudinal midpoint so that the ends of the material are parallel and adjacent to each other. The two parallel ends are then secured together using additional material in any acceptable fashion, leaving an eyelet at the midpoint of the original length of material. Alternatively, in the case of devices having multiple strands braided together, eyelets are sometimes formed by weaving the ends of the strands back into the strands of the body of the device so that an eyelet is fashioned and no strand ends are left exposed at the eyelet end, this method being similar to that used to form an eye-splice in a rope end. Still another method of making an eyelet, described in European Patent Application No. 0106501A1 involves forming the material of the prosthetic into the desired shape under heat and pressure. Another method involves bonding or mechanically attaching a separate eyelet to the remainder of the tissue repair device. These methods are often difficult and time-consuming to manufacture. Many require the use of additional securing material such as sutures or adhesives. Most of them compromise the strength of the completed device so that failure is likely to occur at the point at which the eyelet attaches to the remainder of the device.